This invention relates to fuel filters and contaminant collection bowls for attachment to fuel filters.
As used herein, "filter" refers to devices used to separate out particulate matter from liquids and also to devices, commonly called "separators", used to separate liquid contaminants out from a desired liquid or liquids. As used herein, "fuel" refers to gasoline, oil, or other liquid fuels.
Numerous filter designs use contaminant collection bowls disposed below filter units.
For example, U.S. Pat. No. 4,502,956, Wilson et al., assigned to the assignee of the present invention, discloses a contaminant collection bowl in FIG. 4 which may threadably attach underneath a filter unit and receive contaminants from the fuel flowing through the filter unit.
The following other U.S. patents show various filter assemblies:
______________________________________ U.S. Pat. No. Inventor Issue Date ______________________________________ 2,524,336 Vokes Oct. 3, 1950 3,312,351 Kasten Apr. 4, 1967 4,292,179 Stone et al. Sep. 29, 1981 ______________________________________
The Vokes patent discloses a filter having a collection bowl which threadably attaches at the center of a filter unit and includes seals extending around the peripheral edges of the collection bowl.
The Kasten patent discloses a fuel filter having a contaminant collection bowl including a shoulder, seal, and threads on the upper outside of the collection bowl.
The Stone et al. patent discloses a filter unit having a flow reversing baffle arrangement disposed at an upper part of the filter unit.
Published U.K. application No. 2078536A shows a fuel filter with a collection bowl having attachment threads on its outer wall.
Although the above and numerous other designs have been generally useful in providing filtering, they have been subject to several disadvantages.
Numerous designs having contaminant collection bowls which threadably attach to the bottom of filter units have been quite limited in the amount of pressure they can withstand. For example, the interface between the peripheral wall of the collection bowl and the filter unit may be limited to withstanding a pressure differential of 30 pounds per square inch between the interior pressure and the ambient air. Accordingly, such filter units may only be used in relatively low pressure applications.
A further disadvantage of numerous filter designs is that increased pressure differential between the interior of the filter and the outside may tend to separate the connection between the collection bowl and the filter unit. Regardless of the actual pressure limit for a particular filter construction, it is undesirable to have an increased pressure differential causing a decrease in the sealing force or isolation between the ambient air and the filter interior.
A further disadvantage of numerous filter designs is that they are complex and/or costly in construction.